Ground based Ultrawideband Multistatic Positioning System for VTOL Guidance and GPS Integrity Monitoring

The proposal presents a means of aiding Vertical Takeoff and Landing (VTOL) aircraft position determination and GPS integrity monitoring in Takeoff and Landing Areas (TOLA) by using a low power ground based ultrawideband multistatic radar system that is low cost, compact, portable, and easily deployed. The approach can also be used to detect all aircraft and birds in the airspace above the TOLA. It also provides a means to offer precision helicopter guidance during landing zone brownout conditions. The architecture proposed uses multiple ultrawideband wide-beam radar systems positioned around the landing pad that cooperatively monitor the approach cone to detect and precisely determine the position of airborne targets in the approach cone above them. This information is transmitted to the landing or departing aircraft and can be used as an integrity check for GPS position data. The system works using the delta time of propagation method among multiple radar transceivers. Each of these lsquo;transceiver nodes#39; are situated in the periphery of the landing area. The ground nodes self synchronize and self locate, therefore the system can offer precise landing guidance even in GPS-denied environments. All information is modulated on the radar waveform, making the system independent of any other data communications, also providing graceful failure and robustness if one or more transceiver nodes fails. It will operate with aircraft that have no additional equipment installed, in which case the system can operate as a ground controlled approach controller for vertical operations to helicopters that are equipped with standard radios. It will also detect birds and non-cooperating targets in the airspace above it. Phase I consists of theoretical and simulation based analysis to determine the feasibility of the approach and the requirements for subsystems, with the goal of making system design choices that lead to development of a prototype that will be built and tested in Phase II.